Influence of the Group 14 Element on the Deprotonation of OsH(η⁵-C₅H₅)(C⋮CPh)(EPh₃)(PⁱPr₃) (E = Si, Ge):  Two Different Organometallic Chemistries

Abstract

The complexes OsH(η 5-C5H5)Cl(EPh3)(PiPr3) (E = Si (1), Ge (2)) react with lithium phenylacetylide to give the hydride−alkynyl derivatives OsH(η 5-C5H5)(C⋮CPh)(EPh3)(PiPr3) (E = Si (3), Ge (4)). The structure of 4 has been determined by X-ray diffraction analysis. The distribution of ligands around the osmium atom can be described as a four-legged piano-stool geometry with the monodentate ligands lying in the four-membered face. Treatment of 3 with n-butyllithium and the subsequent addition of methanol, methanol-d 4, and methyl iodide to the resulting solution leads to OsH(η 5-C5H4SiPh3){CC(H)Ph}(PiPr3) (5), OsH(η 5-C5H4SiPh3){CC(D)Ph}(PiPr3) (5- d ), and (6), respectively. Similarly to 3, the reaction of the perdeuterated cyclopentadienyl complex OsH(η 5-C5D5)(C⋮CPh)(SiPh3)(PiPr3) (3- d 5 ) with n-butyllithium and methanol gives OsH(η 5-C5D4SiPh3){CC(H)Ph}(PiPr3) (5- d 4 ). The structure of 6 has been also determined by X-ray diffraction analysis. In this case, the distribution of ligands around the osmium atom can be described as a piano-stool geometry with the metalated carbon atom transoid to the phosphine and cisoid to the hydride. Complex 5 reacts with HBF4 to give the hydride−carbyne derivative [OsH(η 5-C5H4SiPh3)(⋮CCH2Ph)(PiPr3)]BF4 (7), which is stable. Initially, the addition of HBF4 to diethyl ether solutions of 6 also leads to a hydride−carbyne complex, [OsH(η 5-C5H4SiPh3){⋮CCH(CH3)Ph}(PiPr3)]BF4 (8). However, in solution, complex 8 evolves into the hydride−allyl compound [OsH(η 5-C5H4SiPh3){η 3-CH2C(Ph)CH2}(PiPr3)]BF4 (9). The structure of 9 has been determined by X-ray diffraction analysis. The distribution of ligands around the osmium atom can be described as a piano-stool geometry, where the allyl ligand occupies two cisoid positions. Treatment of 4 with n-butyllithium and the subsequent addition of methanol, methanol-d 4, and methyl iodide to the resulting solution gives the germyl−vinylidene complexes Os(η 5-C5H5)(GePh3){CC(H)Ph}(PiPr3) (10), Os(η 5-C5H4D)(GePh3){CC(D)Ph}(PiPr3) (10- d 2 ), and Os(η 5-C5H4CH3)(GePh3){CC(CH3)Ph}(PiPr3) (11), respectively. The protonation of 10 and 11 with HBF4 affords the corresponding carbyne derivatives [Os(η 5-C5H5)(GePh3)(⋮CCH2Ph)(PiPr3)]BF4 (12) and [Os(η 5-C5H4CH3)(GePh3){⋮CCH(CH3)Ph}(PiPr3)]BF4 (13).

Reactions of Osmium–Pinacolboryl Complexes: Preparation of the First Vinylideneboronate Esters

“…The geometry around the osmium atom can be described as a square pyramid similar to that of 3a , with the boron in the apex, trans phosphines (P(1)–Os–P(2) = 165.0(2)°), and the alkynyl ligand trans to the carbonyl group (C(1)–Os–C(9) = 177.53(9)°) occupying the position of the chloride ligand. The Os–C(1) bond length of 2.073(2) Å supports an Os–C(sp) single bond , and indicates a low degree of metal to ligand back-bonding . The C(1)–C(2) distance and the Os–C(1)–C(2) and C(1)–C(2)–C(3) angles are 1.220(3) Å and 177.24(19) and 177.6(3)°, respectively.…”

Metallaaromatic Chemistry: History and Development

“…However, the difference is that 678 – 680 are better regarded as azabutadienyl osmium complexes rather than as osmapyrroles, in view of the solid-state structure of 680 , together with their 13 C NMR spectra. The OsC1 distance in 680 is 2.098(7) Å, comparable to those in osmium alkenyl derivatives, such as [Os­{( E )-CHCHPh}­(CCPh)­(CCH 2 Ph)­(P i Pr 3 ) 2 ]­BF 4 (2.036(9) Å) and (η 5 -C 5 H 4 SiPh 3 )­OsH­(P i Pr 3 )­(η 2 -C 9 H 8 ) (2.082(5) Å), and longer than those in osmaaromatics, such as osmabenzenes 2 (2.00(1) Å) and 24 (1.946(12) and 1.971(12) Å), and the 13 C NMR spectra of 678 – 680 show C1 resonances at 194–197 ppm, shifted almost 30 ppm to higher field compared with those in the starting osmapyrroles 308 – 310 , demonstrating their lower carbenic character.…”

Dehydrative Cyclization of Alkynals: Vinylidene Complexes with the Cβ Incorporated into Unsaturated Five‐ or Six‐Membered Rings

“…For the crystal structure of 3, the thermal ellipsoids are shown at 50 % probability. [21] Scheme 2. For the crystal structure of 7, the thermal ellipsoids are shown at 50 % probability.…”

“…For the crystal structure of 7, the thermal ellipsoids are shown at 50 % probability. [21] Scheme 3. treatment of tetrahydrofuran solutions of 8 with 1.5 equivalents of the alkynal for 24 hours at 60 8C in the presence of 2.0 equivalents of the acid affords 10 in quantitative yield, a mixture of 9 and 10 in a 3:7 molar ratio is formed in its absence. Characteristic spectroscopic features of 9 are: a double triplet at d = 288.6 ppm (J C-Rh = 58.6 Hz and J C-P = 16.0 Hz) and a singlet at d = 197.7 ppm corresponding to RhC a and the carbonyl group, respectively, in the 13 C{ 1 H} NMR spectrum; and a singlet at d = 9.42 ppm and a multiplet at d = 0.15 ppm assigned to the CHO and C b H protons, respectively, in the 1 H NMR spectrum.…”